车辐式张拉结构体型研究与设计

Research and design of structural form of spoke structure

掌握车辐式张拉结构的找形方法和了解体型对结构受力性能的影响,是设计该类轻型屋面的关键,为此结合理论推导和数值模拟方法对这两方面展开研究。首先,引入力密度法用于结构初始平衡态的确定,提出"由形找力再找形"的思路,从而避免了拓展力密度法收敛性差的缺点,成功实现了马鞍形车辐式张拉结构的找形分析。然后,分别从内外环平面投影、外环空间形态以及索桁架形式等多个角度对单、双层车辐式结构的体型进行比选,分析不同体型结构的适用性和结构刚度的主要影响因素。研究结果表明:内外环形状相似对车辐式结构最为有利;马鞍形外环的高差对结构刚度影响很小;凸索桁架能有效提高结构刚度,但应注意避免侧向失稳。

To design a spoke structure, basic knowledge of form finding and how architectural form will affect structural behavior is necessary. Hence this paper presents a research into the above two fields, by theoretical derivation and numerical simulation. First, the force-density method was introduced to find the initial state of equilibrium for the structure. Different from ordinary form-finding processes, the analysis in this article goes from shape to force and then back to shape, which successfully avoids the convergence difficulties often encountered when using general force-density method. Comparison was made among different structural forms of the single-layer and two- layer spoke structures, respectively in terms of planar projections of the inner and outer rings, the spatial shape of the outer ring, and cable truss forms, etc. Through these work, the feasibility of different structural forms and main factors influencing structural rigidity were investigated. Research shows that similar inner and outer rings are preferred for the spoke structure, and the height difference of saddle-shaped outer ring does little to improve structural rigidity. Though convex cable trusses can improve structural rigidity efficiently, they tend to lose lateral stability.